Exposure to low-frequency sound and infrasounds from wind farms: improving information for local residents and monitoring noise exposure
Today ANSES is publishing the results of its assessment of health effects related to low-frequency sounds (20 Hz to 200 Hz) and infrasounds (below 20 Hz) emitted by wind farms. The expert appraisal undertaken by the Agency made it possible, on the one hand, to measure and characterise, in a real-life situation, the infrasound emitted by wind farms, and on the other hand, to analyse the available data on the potential health effects related to exposure to infrasounds and low-frequency sounds. In its conclusions, the Agency underlines that the results of this expert appraisal provide no justification for changing the current exposure limit values or for extending the sound frequencies currently considered in the regulations to include infrasounds and low-frequency sounds. However, the Agency recommends providing enhanced information campaigns for local residents when constructing wind farms, supplementing our knowledge of exposure and undertaking further research into the relationship between health and exposure to infrasounds and low-frequency sounds. The Agency also recommends systematically measuring the noise emissions of wind turbines before and after they are brought into service and setting up continuous noise measurement systems around wind farms, based for example on current practices in the airport sector.
The French regulations on wind turbines introduced a minimum separation distance of 500 metres from any residential dwelling and the classification of wind farms in the regime of Classified Installations for the Protection of the Environment (ICPE, Ministerial Orders of 26 August 2011), although low-frequency sounds and infrasounds were not specifically taken into account.
That said, given the development of wind turbines as renewable sources of electrical energy and the rise in complaints received from local residents, the Ministry of the Environment and Energy submitted a formal request to ANSES to assess the health effects of low-frequency sounds (20 Hz to 200 Hz) and infrasounds (below 20 Hz) from wind farms.
Agency conclusions and recommendations
In order to supplement the data in the scientific literature on exposure to infrasounds and low-frequency sounds emitted by wind farms, ANSES commissioned the National centre fror studies and expertise on risks, environment, mobility, and urban and country planning (CEREMA) to undertake measurement campaigns in the vicinity of three wind farms. The results of these campaigns confirmed that wind turbines are sources of infrasounds and low-frequency sounds. However, the hearing thresholds for infrasounds and low frequencies of up to 50 Hz were not exceeded.
Furthermore, there have been very few scientific studies on the potential health effects of the infrasounds and low-frequency sounds produced by wind turbines. Nonetheless, all of the experimental and epidemiological data currently available show no health effects related to exposure to noise from wind turbines, other than discomfort related to audible noise(1).
However, knowledge recently acquired in animals shows biological effects induced by exposure to high levels of infrasound. These effects have not been described in humans to date, in particular for the exposure levels related to wind turbines found among local residents (long exposure to low levels). It shouls be noted that the connection between these assumptions of biological effects and the occurrence of a health effect has not been documented.
ANSES concludes that current knowledge of the potential health effects of exposure to infrasounds and low-frequency sounds provides no justification for changing the current limit values for noise exposure or for introducing specific limits for infrasounds or low-frequency sounds.
In this context, the Agency recommends:
- improving information campaigns for local residents during the construction of wind farms, in particular by providing them with information about plans for wind farms as early as possible (before public inquiry) and by facilitating participation in public inquiries;
- enhancing the surveillance of exposure to noise, by systematically measuring the noise emissions of wind turbines before and after they are brought into service and by setting up continuous noise-measurement systems around wind farms (based for example on current practices in the airport sector);
- undertaking further research into the relationship between health and exposure to infrasounds and low-frequency sounds, in light of knowledge recently acquired on animals and by examining the feasibility of an epidemiological study designed to observe the health status of residents living near wind farms.
The Agency also reiterates that the current regulations state that the distance between a wind turbine and the first home should be evaluated on a case-by-case basis, taking the conditions of wind farms into account. This distance, of at least 500 metres, may be increased further to the results of an impact study, in order to comply with the limit values for noise exposure..
(1) The hearing threshold is the minimal sound level that a human ear can hear. The lower the sound frequency, the higher the sound intensity has to be for it to be perceived..